Graduation Date

Fall 12-14-2018

Document Type


Degree Name

Doctor of Philosophy (PhD)


Environmental Health, Occupational Health, and Toxicology

First Advisor

Chandran Achutan, C.I.H., Ph.D.

Second Advisor

Elizabeth Lyden, M.S.

Third Advisor

Lorena Baccaglini, Ph.D., D.D.S., M.S.

Fourth Advisor

Risto Rautiainen, Ph.D.


Many farmers have noise-induced hearing loss, yet few use hearing protection when working around loud noise. A point source intervention (storing hearing protection devices near sources of noise) was implemented to help farmers overcome accessibility barriers related to using hearing protection. Intervention farmers (n=53) received education and the point source intervention; control farmers (n=36) received education only. During each year of the study, all farmers completed a questionnaire about their perceptions of hearing protection and participated in an audiometric test at their farm. Ambient sound pressure levels were taken during tests. The main objectives of this dissertation were to evaluate if the point source intervention improved farmers’ perceptions about hearing protection and prevented hearing loss. The onsite audiometric test environments were also assessed.

The first study evaluated factors that influence farmers’ perceptions about hearing protection. These perceptions improved during the study, specifically those related to barriers, self-efficacy, and intent. Older age was associated with positive perceptions of barriers concerning communication and intention to use hearing protection. Having hearing loss (both perceived and measured) was associated with lower intention of using hearing protection. These findings were similar for both intervention and control groups.

The second study, conducting audiometric testing on farms, showed that in most cases ambient noise levels exceeded the American National Institute Standard for audiometric test rooms. Exceedances occurred commonly at lower frequencies, but rarely at high frequencies, which could compromise the reliability of the audiometric test data. Though unconventional, audiometric testing in nonstandard audiometric test environments can detect noise-induced hearing loss.

The final study revealed that a high percentage of farmers have audiograms indicative of noise-induced hearing loss. After adjusting for covariates, farmers’ low-frequency hearing improved over the duration of the study. Farmers that were older had worse low-frequency hearing than younger farmers, and farmers in the control group had worse low-frequency hearing than intervention farmers. Older farmers had worse high-frequency hearing than younger farmers, and left ears had poorer hearing acuity than right ears. The point source intervention did not change the effect from education alone on farmers’ perceptions or their hearing acuity.